This invention relates generally to percutaneous electrical therapy systems for medical use, such as for pain treatment. In particular, the invention relates to a percutaneous electrical therapy system providing sharp point protection.
Electrical therapy has long been used in medicine to treat pain and other conditions. For example, transcutaneous electrical nerve stimulation (TENS) systems deliver electrical energy through electrode patches placed on the surface of a patient""s skin to treat pain in tissue beneath and around the location of the patches. The efficacy of TENS systems in alleviating pain is questionable at best, however.
More recently, a technique in which electrodes are placed through the patient""s skin into the target tissue has been proposed. Percutaneous Neuromodulation Therapy (xe2x80x9cPNTxe2x80x9d) (also sometimes called Percutaneous Electrical Nerve Stimulation or xe2x80x9cPENSxe2x80x9d) using percutaneously placed electrodes achieves significantly better pain relief results than TENS treatments using skin surface electrodes. This therapy is described in Ghoname et al., xe2x80x9cPercutaneous Electrical Nerve Stimulation for Low Back Pain,xe2x80x9d JAMA 281:818-23 (1999); Ghoname et al., xe2x80x9cThe Effect of Stimulus Frequency on the Analgesic Response to Percutaneous Electrical Nerve Stimulation in Patients with Chronic Low Back Pain,xe2x80x9d Anesth. Analg. 88:841-6 ((1999); Ahmed et al., xe2x80x9cPercutaneous Electrical Nerve Stimulation (PENS): A Complementary Therapy for the Management of Pain Secondary to Bony Metastasis,xe2x80x9d Clinical Journal of Pain 14:320-3 (1998); and Ahmed et al., xe2x80x9cPercutaneous Electrical Nerve Stimulation: An Alternative to Antiviral Drugs for Herpes Zoster,xe2x80x9d Anesth. Analg. 87:911-4 (1998). The contents of these references are incorporated herein by reference.
Thus far, PNT practitioners have used percutaneously placed acupuncture needles attached to waveform generators via cables and alligator clips to deliver the therapy to the patient. This arrangement and design of electrodes and generator is far from optimal. For example, the prior art has not addressed the issue of sharps protection for the patients"" caregivers and other bystanders. It is therefore an object of this invention to reduce the exposure of electrical therapy patients"" caregivers to accidental exposure to bloodborne pathogens, microbes, toxins, etc., via an injury caused by unintended contact with a sharp electrode.
It is a further object of this invention to provide a percutaneous electrical therapy system having electrodes and electrode assemblies that are safe, efficacious, inexpensive and easy to use.
Other objects of the invention will be apparent from the description of the preferred embodiments.
The invention is a percutaneous electrical therapy system with sharp point protection. In a preferred embodiment, the system includes a control unit; an electrode assembly adapted to deliver electrical therapy to a patient, where the electrode assembly has an electrode electrically connectable to the control unit, the electrode having a sharp point at a distal end adapted to be inserted into the patient""s tissue; and a sharp point protection assembly operable with the electrode assembly for reducing risk of unintended exposure to the electrode""s point. In some embodiments, the sharp point protection assembly includes a housing to contain at least the sharp point of the electrode when the electrode is in an undeployed state. In some of these embodiments, the sharp point of the electrode may be outside of the housing in a deployed state, the housing being adapted to contain a portion of the electrode in the deployed state. The housing may also be adapted to contain at least the sharp point of the electrode after the electrode has changed from the deployed state to an undeployed state.
In some embodiments, the sharp point protection assembly further has a locking assembly preventing relative movement between the electrode and the housing. The locking assembly may be a spring-biased detent. The system may also include a tool adapted to release the locking assembly and to move the sharp point of the electrode out of the housing. The tool may be further adapted to -move the sharp point of the electrode back into the housing after having moved the sharp point of the electrode out of the housing and to engage the locking assembly to prevent further relative movement between the electrode and the housing.
In some embodiments the electrode assembly has an actuator attached to a proximal end of the electrode, the actuator being disposed within and movable within the housing. The system may also include an actuator tool adapted to interact with the actuator to move the sharp point of the electrode out of the housing. The-actuator tool may be further adapted to move the sharp point of the electrode back into the housing after having moved the sharp point of the electrode out of the housing. The actuator tool may also have an electrical contact adapted to make electrical communication between the electrode and the control unit.
In some embodiments, the housing is adapted to contain none of the electrode when the electrode is in a deployed state in which the sharp point of the electrode has been inserted into the patient""s tissue. The housing may be adapted to contain a plurality of electrodes. The system may also include an actuator adapted to move the electrode out of the housing. The housing may be adapted to contain a plurality of electrodes, the actuator being further adapted to move each electrode out of the housing one at a time.
The electrode assembly further may also include a patch adapted to be placed on the patient""s skin and to support the electrode in the deployed state. The patch may have an opening adapted to surround a portion of the electrode when the electrode is in the deployed state. The patch may also include an annular member disposed in the patch opening and adapted to engage a handle portion of the electrode. The annular member may have a raised portion disposed above the patch and adapted to engage an aperture of the housing.
The system may also include an electrical connector attachable to the electrode handle portion to make electrical communication between the electrode and the control unit.
In some embodiments, the housing is a first housing, with the sharp point protection assembly further including a second housing to contain at least the sharp point of the electrode when the electrode has moved from the deployed state to an undeployed state. The system may also include an actuator adapted to move the electrode into the second housing. The system may also include an electrode grasper adapted to grasp the electrode in response to movement of the actuator, such as a fork adapted to mate with a handle portion of the electrode. The second housing may also be adapted to contain at least the sharp points of a plurality of electrodes, with the actuator being optionally further adapted to move a plurality of electrodes into the second housing.
In some embodiments, the sharp point protection assembly includes an: aperture in the housing adapted to permit the electrode to pass through for deployment of the electrode.
In some embodiments, the system further comprises a movable actuator adapted to move the sharp point of the electrode into the patient""s tissue. The system may also include an actuator limit element limiting movement of the actuator and controlling depth-of insertion of the sharp point of the electrode into the patient""s tissue.
In some embodiments, the system may also include an electrode insertion depth control mechanism.
In some embodiments, the system may also include a deployed electrode holding mechanism adapted to hold the electrode in place after insertion of the sharp point of the electrode into the patient""s tissue.
In some embodiments, the system may also include an electrode insertion axial stabilizer adapted to provide axial stability to the electrode during insertion of the sharp point of the electrode into the patient""s tissue.
In some embodiments, the system may also include an electrode insertion pain reducer adapted to reduce pain experienced by the patient during insertion of the sharp point of the electrode into the patient""s tissue.
In some embodiments, the system may also include an electrode angle of entry controller adapted to control the electrode""s entry angle during insertion of the sharp point of the electrode into the patient""s tissue.
The invention is also a method of performing percutaneous electrical therapy, the method including the steps of providing an electrode assembly having an electrode the electrode having a sharp point at a distal end; inserting the sharp point of the electrode into a patient""s tissue without exposing the""sharp point to anyone but the patient; and applying an electrical signal to the electrode from a control unit. The method may include the step of removing the electrode from the patient""s tissue without exposing the sharp point to anyone but the patient. The method may also include the step of making an electrical connection between the electrode and the control unit. The method may also include the step of, after the inserting step, supporting the electrode in the patient""s tissue.
In some embodiments, the inserting step includes the step of using the electrode assembly to guide electrode entry angle. In some embodiments, the inserting step includes the step of using an introducer to guide electrode entry angle. In some embodiments, the inserting step includes the step of providing axial stability to the electrode during insertion. In some embodiments, the inserting step includes the steps of placing a housing adjacent the patient""s tissue; and moving the sharp point of the electrode out of the housing and into the patient""s tissue. This method may also include the step of placing a patch on the patient""s tissue prior to the step of placing a housing, in which the step of placing a housing includes the step of placing the housing adjacent the patch. In this method, the patch may have an opening, with the moving step including the step of moving the sharp point of the electrode out of the housing, through the opening and into the patient""s tissue. The method may also include the step of mechanically supporting at least a portion of the electrode with the patch.
In some embodiments of the method, the moving step includes the steps of moving the entire electrode out of the housing; and removing the housing from the patient""s tissue. In some embodiments, the housing is a first housing, the method further including the step of removing the electrode from the patient""s tissue into a second housing without exposing the sharp point to anyone but the patient.
In some embodiments, the method includes the step of removing the electrode from the patient""s tissue into the housing without exposing the sharp point to anyone but the patient.
The invention also includes an electrode assembly and sharp point protection assembly for a percutaneous electrical therapy system as described above, apart from the control unit.
The invention is described in further detail below with reference to the drawings.